The rhizosphere bacteria (rhizobacteria) with beneficial effects on plant growth are often termed PGPR (Plant Growth-Promoting Rhizobacteria) and benefit the crop plant during various stages of its growth from sowing/planting until the harvest. Fluorescent pseudomonads in soil and rhizosphere have in numerous studies been demonstrated to exert plant growth promotion effects in several agricultural crops (Kloepper et al., 1980 a, b; Brisbane et al., 1989; DeFreitas and Germida 1991) and also to suppress plant diseases (Hemning, 1990, O'Sullivan and O'Gara, 1992, Weller, 1988, Hökeberg et al., 1997).
Under experimental conditions several fluorescent pseudomonads have been verified as potential agents to increase emergence and yield of agricultural crops, such as wheat (Kropp et al., 1996), mustard (Deshwal et al., 2006), sugar beet (Suslow and Schroth 1982), potato (Kloepper et al., 1980; Howie and Echandi, 1983), radish (Kloepper and Schroth 1978; Davies and Whitbread 1989) and spinach (Urashima et al., 2006). Several mechanisms connected to their plant growth promoting activity are well studied and described. These, among others, include root colonization ability (Benizri et al., 2001), capacity to produce a wide range of enzymes and hormones (Vivekananthan et al., 2004; Lucy et al., 2004, Patten and Glick 1996; García de Salamone et al., 2001) as well as other metabolites with often antimicrobial activity (Loper and Buyer 1991; Dowling and O'Gara 1994). Examples of patents/patent applications covering different areas of their activity are also available and involve mostly strains/isolates with biocontrol properties. Patent/patent applications on fluorescent pseudomonads with plant growth promoting properties cover most often an active component (bacterial strain) of the invention in combination with description of screening and test methods needed in order to select desired isolate(s). The following patent applications, which are hereby incorporated, provide some examples on the inventions covering fluorescent pseudomonads with plant growth promoting and/or biocontrol properties: WO/1987/000194, US1996/5503652, WO0051435, US1996/5503651, US2002/6447770, and US2002/6495362.
Despite the literature and patent/patent applications listed above, there is, so far no other isolate belonging to the species of Pseudomonas azotoformans that has been shown and proven to be able to consistently improve emergence, growth and yield of many important agricultural crops during several years of field experiments. In contrary, a previously studied soil-originating isolate of Pseudomonas azotoformans did not show any significant growth promoting effects in experiments with rice (Piao et al., 2005). The only brief information on plant growth promoting properties of isolates of Pseudomonas azotoformans, which concerns rhizome-associated bacterial communities of healthy reed stands in Lake Velencei, Hungary (Micsinai et al., 2003), is not based on any experimental data confirming its plant growth promoting properties.